Circuits and apparatus for operating electric discharge lamps



u 1936- w. F. WESTENDORP 2,043,023

cmcun-s ANDEAPPARATUS FOR OPERATING ELECTRIC DISCHARGE LAMPS Filed Feb.23, 1955 Fig; 1

High Pressur- Mercury ya arLnm lnventorz Willem F. Westenolor Histtorneg.

Patented June 2, 1936 UNITED STATES PATENT OFFICE CIRCUITS AND APPARATUSFOR OPERAT- ING ELECTRIC DISCHARGE LAMIPS Willem F. Westcndorp,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York My invention relates to electric-discharge lamps, and moreparticularly to a circuit and I apparatus for operating them.

One object of my invention is toprovide an improved circuit andapparatus for regulating the voltage and current in a series operateddischarge lamp throughout the starting and operating period.

Another object of my invention is to provide means for converting intolight the available energy not used by the discharge lamp during itsoperating period.

For a better understanding of my invention, together with other andfurther objectsthereof, 1 reference is had to the following description,

taken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

In the accompanying drawing, Fig. 1 is a sche- 20 matic diagramillustrating my invention, and

Figs. 2 and 3 are modifications thereof.

Referring to Fig. 1 in detail, a transformer Ill.

8 The electric-discharge lamp I4 is of the type In this type of lamp ametal vapor, such as mercury, for example, is used, which duringoperation of the lamp rises to a pressure substantially equal toatmospheric pressure, and the lamp is, therefore, usually referred to ashigh pressure mercury vapor lamp. Among the characteristics of this typeof lamp are a. high current and comparatively low voltage at startingapproximately 5 45 amperes at 20 volts, a high voltage and low currentduring operation, approximately 2.9 amperes at 155 volts. During coldweather it is necessary to heat the lamp to 0 C. or above before it willtake even a starting current. Since it is desira- 50 ble to operatethese lamps on standard series street lighting circuits in which aconstant current is maintained, special apparatus must be provided tocontrol the voltage and to make use of the energy which is available foreach lamp. 55 Referring to Fig.- 1 again, it will be apparent describedin United States Patent 1,948,261, assigned to the assignee of thepresent invention.

that incandescent lamp l5 being connected in multiple with the lamp l4will be energized at the instant that the current flows in circuit l2.As

stated above, the current flowing through' the di'schargelamp Id at thebeginning of the operation is comparatively high (5 amps.) so that acomparatively low voltage (20 v.) is obtained due to the reactance ofthe transformer. The incandescent lamp l5 takes a negligible amount ofcurrent at this voltage. During warm weather a discharge lamp will startvery quickly and the operating current will immediately diminish therebyraising the voltage across the two lamps. When normal operating voltage(in the present instance 155 v.) is reached the incandescent lampcarries its full load current and the discharge lamp acts as a voltageregulator. The transformer i0 is designed to furnish the necessarycurrent at the normal operating voltage for both lamps. In cold weather,however, the discharge lamp M will allow no current to pass so that thevoltage across the two lamps will rise and'energize coil l6 which, asstated above, is in multiple with the two mentioned lamps. This coil isarranged to move its armature when a predetermined voltage is reached;in the present instance at approximately 200 volts. Its contacts arethereby closed and the circuit to the third lamp is established. Thiscircuit may be traced from winding I3, through conductor 2|, lamp 20,conductor 22, contacts I 8 and I9, contact bar I! and through conductor23 to the winding l3. As long as the discharge lamp l4 does not allowcurrent to pass, the coil l6 will maintain the circuit to lamp 20closed. The two lamps l5 and 20 will, therefore, convert the-availableenergy into light and can be mounted close enough to the discharge lampto raise the temperature thereof by radiation. When the temperature ofthis lamp is raised, the discharge willstart and the voltage across thislamp will fall to a low value, e. g. 20 volts, thereby reducing thecurrent in coil l6 which drops the contact bar I! and disconnects theincandescent lamp 20. As this discharge lamp I 4 then reaches normaloperating conditionsthe voltage again rises and the incandescent lampl5, which remains in the circuit, again reaches full brilliance and thedis- V discharge lamp I4 is connected across a secondary winding 30having a low voltage tap 3| across which the incandescent lamps l5 and20 are connected. The relay coil 26 in this figure operates two contactbars 32 and 33. When the lamp I5 is energized, the coil 26 is alsoenergized and establishes a circuit to lamp M by means of its contactbar '32 and to coil l6 by means of its contact bar 33.

The circuit to the incandescent filament lamp l5 may be traced fromwinding 30 to conductor 34, relay coil 26, lamp l5, conductor 2| to tap3| on the winding 30. The circuit to the discharge lamp ll may be tracedfrom the winding 30 through the conductor 35, the lamp II, the conductor38, the relay contacts 31 and 38, the bar 32, the conductor 34, to theopposite terminal of the winding 30. By this means each lamp l5 and I4may be operated at its most eificient voltage and the actual division ofpower between the" lamps remains the same as in the previous circuits asillustrated in Figs. 1 and 2.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In combination, a transformer having a substantially constant currentprimary circuit, an electric discharge lamp having a variable energydemand during starting and operating periods and an incandescentfilament lamp, said lamps being connected to said transformer inmultiple whereby the substantially constant cur-=' rent available fromsaid transformer is proportioned between said lamps. Y

2. In combination, a transformer having a substantially constant currentprimary circuit, an electric discharge lamp having a high currentstarting characteristic and a low current operating characteristic andan incandescent filament lamp, said lamps being connected to saidtransformer in multiple whereby the available power is proportionedbetween said lamps during the starting and operationg periods of saiddischarge lamp.

3. In a lighting unit, the combination of a transformer having asubstantially constant current in its primary winding, an incandescentfilament lamp and an electric discharge lamp connected in multipleacross the secondary of said transformer, a second incandescent filamentlamp and means for automatically connecting said incandescent lamp inmultiple when said discharge lamp fails to start.

4. In combination, a transformer having a sub stantially constantcurrent primary circuit, a secondary winding, an electric dischargelamp, an intermediate voltage tap on said secondary winding, anincandescent filament lamp connected thereto, and means responsive tocurrent flowing through said incandescent lamp for connecting saiddischarge lamp across said secondary winding. V

5. In combination, a transformer having a substantially constant currentprimary circuit, a secondary winding, an electric discharge lamp, anintermediate voltage tap on said secondary winding having anincandescent lamp connected thereto, means responsive to current flowingin said incandescent lamp for connecting said discharge lamp across saidsecondary winding, and means responsive to an increase in voltage abovethe operating voltage of said discharge lamp 35 for connecting a secondincandescent filament lamp in multiple with said first incandescentfilament lamp.

WIILEM F. WESTENDORP.

